The present invention relates to metal-oxide-semiconductor (MOS) devices, and particularly to metal-oxide-semiconductor devices capable of operating at higher voltages.
In many electrical applications MOS devices, like high voltage integrated circuits, smart power devices, MOSFET's, and integrated gate bipolar transistors (IGBTs), are used to operate under voltage control and facilitate control circuit design. These devices, in general, have a channel forming area at a surface layer of a semiconductor substrate and a MOS structure on the surface to form a channel forming area.
These MOS devices have a problem in that they cannot operate at high voltages. The reason is that when a voltage is applied across the drain electrode and the source electrode during the off state, a field concentration occurs at the drain layer leading to breakdown at low voltages. It is preferable, especially in high power applications, to utilize devices able to withstand higher voltages.
The present inventor has discovered a MOS device operable at significantly higher voltages that solves the prior art problem by preventing this field concentration from occurring.
It is therefore an object of the present invention to describe a metal-oxide-semiconductor device with a breakdown voltage higher than previously available.